Graphene containing conductive inks for electrical contacts to power semiconductor devices

Gallium nitride is one of the materials of choice for high power, high frequency and high temperature applications. However, one key component of GaN transistors and diodes is the Schottky contact and it can create a weakness in the device when high leakage currents occur at small isolated regions containing dislocations. It has been reported that the electron affinity increases at certain defects reducing the Schottky barrier height.[1] The metals used currently as Schottky contacts perform poorly due to their limited range of work functions and pinning of the Fermi level by electronic states at the metal-semiconductor interface. Therefore, we are investigating the use of graphene containing inks produced by Vorbeck Materials for the formation of Schottky contacts. This material is expected to change its electronic characteristics such as the work function based on how it is functionalized. Therefore by coming up with the proper functionalization we may obtain a contact material with very low reverse leakage by increasing the material's work function. Other benefits that graphene inks would provide as electrical contacts are excellent electrical and thermal conductivity. Results of applying this contact material to silicon and GaN Schottky diodes will be discussed and compared.